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a;\(\frac{x}{-3}=\frac{4}{y}\)
\(\Rightarrow xy=-12\)
\(\Rightarrow x;y\inƯ\left(-12\right)=\left\{\pm1;\pm2;\pm3;\pm4;\pm6;\pm12\right\}\)
Xét bảng
x | 1 | -1 | 2 | -2 | 3 | -3 | 12 | -12 | 6 | -6 | 4 | -4 |
y | -12 | 12 | -6 | 6 | -4 | 4 | -1 | 1 | -2 | 2 | -3 | 3 |
Vậy.................................................
b,\(\frac{2}{x}=\frac{y}{-9}\)
\(\Rightarrow xy=-18\)
\(\Rightarrow x;y\inƯ\left(-18\right)=\left\{\pm1;\pm2;\pm3;\pm6;\pm9;\pm18\right\}\)
Xét bảng
x | 1 | -1 | 2 | -2 | 3 | -3 | 6 | -6 | 9 | -9 | 18 | -18 |
y | -18 | 18 | -9 | 9 | -6 | 6 | -3 | 3 | -2 | 2 | -1 | 1 |
Vậy...................................
c;\(\frac{x}{3}=\frac{y}{7}\)
\(\Rightarrow xy=21\)
\(\Rightarrow x;y\inƯ\left(21\right)=\left\{\pm1;\pm3;\pm7;\pm21\right\}\)
Xét bảng
x | 1 | -1 | 3 | -3 | 7 | -7 | 21 | -21 |
y | 21 | -21 | 7 | -7 | 3 | -3 | 1 | -1 |
Vậy..........................
![](https://rs.olm.vn/images/avt/0.png?1311)
X + 1+2+3+4+5-6-7-8-9=1-2-3-4-5+6+7+8+9
X+ (-15) = 17
X = 17-(-15)
X = 32
vậy x = 32
tk nha
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{x+7}{45}=\frac{x-3}{15}\)
\(\Rightarrow15\left(x+7\right)=45\left(x-3\right)\)
\(\Rightarrow15x+105=45x-135\)
\(\Rightarrow15x-45x=\left(-105\right)-135\)
\(\Rightarrow-30x=-240\)
\(\Rightarrow x=8\)
\(\frac{x+7}{45}=\frac{x-3}{15}\)
\(\Rightarrow15\left(x+7\right)=45\left(x-3\right)\)
\(15x+105=45x-135\)
\(15x-45x=-135-105\)
\(-30x=-240\)
\(x=-240:\left(-30\right)\)
\(x=8\)
Vậy x = 8
![](https://rs.olm.vn/images/avt/0.png?1311)
TL:
x = 8
Giải thích :
\(\frac{x+7}{45}=\frac{x-3}{15}\)
\(\Rightarrow15\left(x+7\right)=45\left(x-3\right)\)
\(\Rightarrow15x+105=45x-135\)
\(\Rightarrow15x-45x=\left(-105\right)-135\)
\(\Rightarrow-30x=-240\)
\(\Rightarrow x=8\)
TL
x=8
nha
HT